1. Technical Field
The present invention relates to an electronic sphygmomanometer, and particularly relates to the electronic sphygmomanometer that detects a volume change of a blood vessel as a pressure change of a cuff, namely, an amplitude of a pressure pulse wave, and calculates a blood pressure value using the detected amplitude of the pressure pulse wave.
2. Background Art
Electronic sphygmomanometers for measuring a blood pressure using an amplitude of a pressure pulse wave (hereinafter, “a pulse wave amplitude”) like in an oscillometric method have been conventionally present. The oscillometric method is a method for pressurizing or depressurizing a cuff wrapped around a part of an organism to acquire a volume change of the cuff obtained from a volume change of a pressurized blood vessel as a pressure change of the cuff, namely, the pulse wave amplitude and calculating a blood pressure.
In such electronic sphygmomanometers, it is found that because a pressure and a volume of a cuff are not in proportional to each other due to a cuff property, detection accuracy of a volume change in a blood vessel varies according to an arm circumference and pressures of a cuff. That is to say, even if the same blood pressure values are obtained, an error is caused in a level of the pulse wave amplitude due to factors such as differences in the cuff pressure and the arm circumference. For this reason, such factors are error factors of the blood pressure value.
The following method has been conventionally proposed for preparing a volume change property.
For example, Japanese Unexamined Patent Publication No. 5-329113 (Patent Document 1) describes a method for preparing a volume change property of a cuff with respect to a cuff pressure in advance and converting a signal of the pressure change of the cuff into a volume change so as to measure a blood pressure value using the volume change.